Adjustable contact nozzle and retractable arcing chamber for gas blast circuit breakers

ABSTRACT

A high voltage gas blast circuit breaker has a stationary contact with a central opening and an axially projecting neck. A movable contact, mechanically connected to the same operating rod that temporarily opens a blast valve, moves axially with respect to the stationary contact. A cylindrical baffle surrounds the stationary contact and is pressed against the stationary contact during gas blast conditions to form a gas blast channel which extends through the center of the stationary contact. Biasing springs bias the baffle axially away from the stationary contact.

[ ADJUSTABLE CONTACT NOZZLE. AND

RETRACTABLE ARCING CHAMBER FOR Sept. 17, 1974 FOREIGN PATENTS ORAPPLICATIONS 524,983 8/1940 Great Britain 200/148 GAS BLAST CIRCUITBREAKERS 1,358,550 3/1964 France 200/148 [75] Inventor: John H. Golota,Los Angeles, Calif. 73 Assignee: I-T-E Imperial Corporation, Prim?Examiner-Robert Philadelphia Attorney, Agent, or FirmOstro1enk, Faber,Gerb and Soffen [22] Filed: Nov. 6, 1967 21 Appl. No.: 680,778 I 57ABSTRACT A high voltage gas blast circuit breaker has a station- [52]US. C1. 200/148 R, ZOO/148 BV a y Contact with a central opening and anaxially pro- [51] Int. Cl. H0111 33/82 je ting neck, A movable contact,mechanically con- [58] Field of Search 200/148, 148.2, 160; nected tothe same operating rod that temporarily 151/5 opens a blast valve, movesaxially with respect to the stationary contact. A cylindrical bafflesurrounds the [56] References Cited stationary Contact and is pressedagainst the stationary UNITED STATES PATENTS Contact during gas blastconditions to form a gas blast 3,214,545 /1965 Cromer 200/148 channelwhich F f throPgh h center of 1116,5121" 3,218,421 11 1965 Latour 200148 tlonary Contact Blfdsmg Sprmgs blas the baffle aXlally 3,339,0468/1967 Giammona et 200/148 ay from the stationary contact. 3,436,5054/1969 MCKeough ZOO/148 3,441,692 4 1969 Cromer et a1 200 148 x 3 Clams33 Drawmg F'gures l2 1 1 :73 154 3; f/ 43 J 1\ 3 1 44 15 d (1J0! /Z7 j,

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PATENTEB 71974 3.836.741 saw me or 12 ADJUSTABLE CONTACT NOZZLE ANDRETRACTABLE ARCING CHAMBER FOR GAS BLAST CIRCUIT BREAKERS This inventionrelates to high voltage gas blast circuit breakers, and moreparticularly relates to a retractable arcing. chamber for gas blastcircuit breakers.

This application is related to copending applications Ser. No. 680,777,filed Nov. 6, 1967, in the name of John H. Golota, entitled AxiallyVented Contact and Interrupter Structure for Gas Blast Circuit Breakers;Ser. No. 547,621, filed May 4, 1966, in the name of Daniel H. McKeough,entitled Slide Valve for Gas Blast Breakers, now US. Pat. No. 3,436,505;and Ser. No. 680,849, filed Nov. 6, 1967, in the name of Daniel H.McKeough, entitled Dead Tank Gas Blast Circuit Breaker, and are allassinged to the assignee of the present invention.

In accordance with, the present invention, there is provided an arcingchamber contact nozzle arrangement in an axial flow gas blast circuitbreaker which employs a movable arcing chamber held in place bydifferential, gas. pressure during interruption. This chamber isretracted or moved relative to' the stationary contact nozzle to providea complete break or gap with decay of chamber gas pressure followinginterruption and blast valve cutoff.

The invention provides a stationary nozzle contact assemblyand an arcingchamber free to engage the contact nozzle areola with increasing chambergas pressure. Engaging or mating surfaces are shaped to conform closelyso as to effectively seal the juncture and direct all gasflow outthrough the throat of the nozzle contact. Gasket sealsmay be used oneither mating surface if desired. In addition, the stationary contactassembly absorbs all end thrust from the arcing chamber to effectivelyeliminate all axial tensile forces on the arcing chamber walls. Theremainder of the stationary contact assembly allows for radial, axialand angular alignment of the nozzle with the arcing chamber and movingcontact.

Accordingly, a primary object of this invention is to improve theinterruption ability of a high voltage gas blast circuit breaker.

Another object of this invention is to provide a novel retractable arcchamber for gas blast interrupters which provides good control of thegas pressure during operation.

Another object of this invention is to provide a novel contactarrangement for gas blast interrupters which simplifies mounting thereofand provides improved operation.

These and other objects of this invention will become apparent from thefollowing description when taken in connection with .the drawings, inwhich:

FIG. 1 is a side view, partially in section, showing an entire assemblyof the interrupters and operating mechanism of a circuit breaker made inaccordance with the presentinvention. A

FIG. 2 is a cross-sectional view of one of the inter,- rupter assembliesof FIG. 1.

*FIG. 3 is a top view of the upper adaptor of FIGS. 1 and 2.

FIG. 4 is a cross-section of FIG. 3 taken across the section line 4 4 inFIG. 3.

FIG. 5 is a top view of the lower adaptor of FIGS. 1 and 2 which islocated below the upper adaptor of FIGS. 3 and 4.

FIG. 6 is a cross-sectional view of FIG. 5 taken acrossthe section line6 6 in FIG. 5.

FIG. 7 is a top view of the stationary contact of the interrupter ofFIG. 2.

FIG. 8 is a cross-section view of the contact of FIG. 7 taken across thesection line 8 8 in FIG. 7.

FIG. 9 is a top view of the movable contact assembly of FIGS. 1 and 2. i

FIG. 10 is a cross-section of FIG. 9 taken across the section line 10 10in FIG. 9.

FIG. 11 is a top view of the locking disk of FIG. 10.

FIG. 12 is a cross-section view of FIG. 11 taken across section line 1212 in FIG. 11.

FIG. 13 is a front view of one of the contact fingers of FIG. 10.

FIG. 14 is a top view of the contact finger retainer of FIG. 10.

FIG. 15 is a cross-section view of FIG. 14 taken across the section line15 15 in FIG. 14.

FIG. 16 is a top view of the interrupter support.

FIG. 17 is a cross-section of FIG. 16 taken across the section line 1717 in FIG. 16.

FIG. 18 shows a top view of the interrupter tube flange.

FIG. 19 is a cross-section of FIG. 18 taken across section line 19 19 inFIG. 18.

FIG. 20 is a plan view, partially in section, of the movable interruptertube assembly.

FIG. 21 is a plan view of the retainer of FIG. 20.

FIG. 22 is a side view of FIG. 21.

FIG. 23 is a top view of the cylindrical air control valve.

FIG. 24 is a cross-section view of FIG. 23 taken across section line 2424 of FIG. 23.

FIG. 25 is a top plan view of a three-pole dead tank circuit breakerarrangement using the interrupters of FIGS. 1 and 2 for each respectivepole.

FIG. 26 is a side plan view of FIG. 25.

FIG. 27 is an end plan view of FIG. 25.

FIG. 28 shows a partial cross-sectional end view of one pole of FIGS. 25to 27.

FIG. 29 shows a partial cross-sectional side view of one pole of FIGS.25 to 27.

FIG. 30 is a partial cross-sectional view of one of the terminalbushings of FIGS. 25 to 29.

FIG. 31 is a top, partial cross-sectional view of FIGS. 28 and 29.

FIG. 32 is a front plan view of a portion of the operating mechanism ofFIGS. 28 and 29.

FIG. 33 is a cross-sectional view of FIG. 32 taken across section line33 33 in FIG. 32.

FIG. 1 shows the assembly of the novel interrupter assembly of theinvention, and illustrates two series connected interrupters l0 and 11.Interrupters 10 and 11 are identical and will be described in detailhereinafter. The interrupters l0 and l l are controlled by an operatingmechanism, generally indicated by numeral 12, which is supported on atank housing 13. Tank housing 13 is, in turn, carried on an elongatedinsulation pedestal 14 which may be carried on a high pressure gassupply at ground potential, as will be'later'described in FIGS. 25 to29'.

Each'of interrupters l0 and 11 areconnected at their tops to insulatorbushings, to be later described, which are connected in series with thecircuit to beprotected. The connection surrounding the tops ofinterrupters I0 nate through openings 25 to 30. The upper surface ofadaptor 18 then has a conical surface 31 which engages the conical lowersurface 32 of insulator 17 to permit angular adjustment of insulator 17,as shown by arrow 17a in FIG. 2. A series of bolts, such as bolt 33having washer 34, then extend through openings, such as through-opening28, to secure upper adaptor 18 to insulator 17.

A lower adaptor 35 is then provided, as shown in FIGS. and 6, which hasa plurality of extending ears containing through-openings 36 to 41extending from acentral web 42. An annular groove 43 is cut through theweb 42 so that it is held by the material of the extending ears. Aplurality of through-holes and aligned tapped openings 44 to 49 are thenformed in the web 42, and the interior web surface is threaded by thread50. The through-openings 36 to 41 in lower adaptor 35 are then alignedwith tapped openings m in upper adaptor 18 (FIG. 3), and suitable boltsand washers, such as bolt 51 and washer 52, shown in FIG. 1, secureshield 15 and adaptor plates 18 and together.

The interior thread of web 42 of lower adaptor 35 receives thestationary contact 53 of the interrupter. Contact 53 is "shown in FIGS.7 and 8 and comprises a main body 54 having a central opening 55 whichtapers outwardly to define a blast orifice. The outer diameter of body54 is threaded with a thread 56, and an arcresistant insert 57. Thread56 of contact 53 is then threaded into thread 50 of lower adaptor 35 andis secured therein by tightening a plurality of bolts, such as bolt 57a,shown in FIG. 2,v which pass through the through-openings in the lowerpart of web 42 and into the threaded opening 44. As these bolts aretightened, the upper and lower interior portions of web 42 tighten onthread 56 to hold contact 53 securely. Note that the axial contactposition is easily controlled by threading contact 53 more or less intothread 50, as shown by arrow 58 in FIG. 2. Moreover, by providingclearance between the outer diameter of the bolts, such as bolt 51,which secure lower adaptor 35 to upper adaptor 18 and the correspondingthrough-openings, such as opening 36, lateral adjustment can be obtainedfor contact 53, as shown by arrow 59 in FIG. 2.

The movable contact assembly of FIGS. 1 and 2 is best shown in detail inFIGS. 9 to 15.

The movable contact assembly is composed of a circular cluster ofcontact fingers 60 to 71, each having generally rectangular shape, shownin FIG. 13 for contact 60. Each of the contact fingers have arcresistantinserts secured thereto, such as inserts 72 and 73, secured to contacts60 and 66, respectively. Each of the contact fingers have twoprojections, such as projections 74 and 75, for finger 60 in FIGS. 10and 13, which receive biasing leaf springs, shown as'leaf springs 76 and77 for contacts 60 and 66 which bear on insulation buttons 78 and 79,respectively.

The contacts 60 to 71 are laid on the outer notches v in contactretainer 80, shown in FIGS. 14 and 15, and are held on the retainer 80by a spring retainer 81 which encircles the central exterior portions ofthe 4:: contacts. A spring 82, shown in FIG. 10, extends around thebottom interior of the contacts. A locking disk 83, shown in FIGS. 11and 12, havin a central opening 84, is inserted into'retainer 80 .andinto engagement with shoulder 80a of retainer 80. A

movable arcing contact is then secured to locking disk 83, as by pins.extending from disk 83 to arcing contact 85. It will be noted thatarcing contact 85has a bottom flange 85a which has an outer diameterthat engages the arcing contact tips of the arcing Contact fingers tolimit their inward collapse and to provide commutation of the arc frominsert 72 to contact 85 during opening. The interior of arcing contact85 is threaded and threadably receives the end of operating shaft 86 andis secured thereon by locking nut 76, best shown in FIG. 10.

FIGS. 16 and 17 show the interrupter support 88 for slidably holding themovable contact assembly of FIG. 10. Support 88 contains a centralstationary contact portion 89, the outer end of which slidably receivesthe lower endsof contact fingers 60 and 71 in slidable engagement.Central portion 89 is connected to base portion 90 by four streamlinedwebs 91, 92, 93 and 94 (FIG. 16). Base 90 has two sets of fourthroughopenings 95 to 98 and 99 to 102 in the corners thereof, and a setof through-openings 103 to 106, respectively, in the corners thereof.Two rings 107 and 108 of insulating material, shown in FIG. 2, arecontained in internal grooves 109 and 110, respectively, in the centralopening 111 of central portion 89, shown in FIGS. 15 and 16, to sealaround the operating rod 86, and to provide electrical insulationbetween rod 86 and base 90 as shown in FIG. 2. Support 88 is thenfastened to support casting sections 112 and 113 (which areparts of acommon casting) of FIGS. 1 and 2, as by bolts which pass throughopenings 95 to 102 into appropriate tapped openings incasting sections112 and 113, partly shown in FIG. 1 by bolts 1 14 and 115'. Note thattheoperating rod 86 passes through a suitable opening, which may besealed, in casting section 112.

An interrupter tube assembly, arranged above the I support 88 andenclosing the contact area is carried on a flange 116, shown in FIGS. 18and 19. Flange 116 comprises an extending cylindrical portion 117 andfour through-openings 118 to 121 in the comers thereof. Flange 116 issecured to support 88 beneath it by the four bolts (not shown) extendingthrough openings 118 to 121.in flange 116 and respective openings 95 to98 in support 88 (FIG. 16), which bolts are threaded into the castings112 and 113. V

An interrupter tube 122 is then secured to extension 117 in any suitablemanner, where tube 122 is of glass fiber, or the like. Tube 122 thenslidably receives the movable interrupter tube portion 123, which ismovable in the direction of arrow 124,. with a gasket between thesurfaces of tube 122 and sliding portion 123.

The sliding interrupter tube portion 123is best understood by reference'to FIGS. 20, 21 and 22. Referring to FIG. 20, the movable interruptertube comprises an outer insulation cylinder 125 and an-inner liningcylinder 126 which secure, between them, an insulation lining disk 127and baffle ring 128. The bottom of the cylinders are secured by ring 129which has a Iowerlip extending below liner 126 and a plurality of pins,such as pin 130, which extend into cylinder 125.

Four pins, three of which are shown as pins 131, 132 and 133 in FIG. 20,then extend into openings in ring 129 and are locked therein by suitablelocking pins, such as locking pin 134 for pin 133. Pins 131 and 133 areseen in FIG. 2 with the four pins disposed from one another. Each of thepins have enlarged heads such as head 135 of pin 133, shown in FIG. 20,which are captured in housings, such as housings 136, 137 and 138 forpins 131 to 133, respectively. A split retainer spring disk 139, shownin FIGS. 21 and 22, which is split at portion 140, has four openings 141to 144 for receiving the four spring housings, including housings 131,132 and 133, as shown in FIG. 20. Internal springs, such as spring 145of housing 138, then bias the housings 136 to 138 toward the ring 129and external springs 146, 147 and 148 bias plate 139 toward the ring129.

In assembling the movable interrupter tube, it will be noted in FIG. 2that the periphery of plate 139 is captured between adaptor 116 andsupport 88, with ring 129 beneath shoulder 150 in stationary tubeportion 122. Also, it is seen that the baffle ring lies just adjacentthe lower tapered surface of contact 53.

The operating mechanism for moving operating rod 86 is best shown inFIG. 1 where it is seen that the casting sections 112 and 113 have adownwardly extending portion 151. Portion 151 has two slots for passingears 152 and 153 of cylindrical valve 154. The ears 152 and 153 are thenconnected to links 154a and 155, respectively, which are, in turn,pivotally connected to operdisk 187 by bolt means, such as bolt 188.Sealing rings 189 and 190 prevent leakage between rings 185 and 186.Ring 186 carries a main valve seat 191 which cooperates with the bottomof cylinder 158. Note that a sliding seal 192 is formed between disk 186and shaft 177, and that a buffer 193 is connected to the top of disk 187to receive the bottom of hub 159 when valve 158 moves down.

ating rods 86 for interrupters 10 and 11 through suitable couplings 156and 157, respectively.

A blast valve is best shown in FIGS. 23 and 24 as comprising acylindrical body 158 connected to a central hub 159 by streamlined arms160 to 163. The ends of cylindrical body 158 are formed with valve diskengaging sections 164 and 165. The interior opening in hub 159 isprovided with a thread 166. The two ears 152 and 153, shown above, thenextend outward from cylindrical body 158.

Cylindrical valve body 158 then moves between an upper and lower valveseat. The upper valve seat is composed of an upper disk 167 which issecured to casting section 113 and a lower disk 168 which is bolted todisk 167 as by bolts such as bolt 169. Disk 168 is sealed with respectto casting section 113 by seal ring 170 and carries a main valve seatring 171 which cooperates with the upper end of cylindrical valve body158. A valve retaining disk 172 is bolted to disk 168 as by bolt 173 andsecurely holds ring 171 in position. Disk 172 also has a buffer disk 174bolted thereto as by bolt 175 which engages nut 176 when the valve 154is :moved upwardly.

Hub 159 is threaded on operating shaft 177 and is locked in place by nut176 which is also threaded on ring 182 having a sealing ring 183engaging ring 182 is provided with a sliding seal ring 184 whichsurrounds the lower portion of cylinder 158.

- The bottom of members 181 carries a ring 185. Ring 185 is connected tovalve disk 186 and valve retainer The ring is welded to high pressuretank 13 which is composed of welded upper and lower halves 200 and 201,respectively. High pressure gas, such as air and preferably sulfurhexafluoride, is then supplied to the interior of tank 13 from thecentral channel through insulator 14 which is appropriately connected atits bottom to a high pressure gas source, as will be later described.

An elongated operating shaft 203, which extends coaxially with insulator14, can be moved up and down by operating means, to be later described,which may be carried at ground, and is connected to shaft 177 by ashock-absorbing coupling.

FIG. 1 further shows a small tubular member extending downwardly andinto the annular space between pedestal l4 and rod 203, and arranged sothat any gas which condenses on the surface of housing 13 will flowdownwardly and freely through the annular space without impinging on theinsulating surfaces of members 14 and 203.

The coupling as shown in FIG. 1 is comprised of a spring 204 capturedbetween rings 205 and 206 at its top and bottom, and an outer cylinder207 on its outer periphery. Ring 205 is captured beneath a shoulder inshaft 177 as shown, while ring 206 is held by nuts 208 and 209 which arethreaded on the threaded bottom of shaft 177. Outer shells 210 and 211each have threaded interiors, threaded on the outer threaded surface ofcylinder 207 with extension 212 of shell 210 bearing on ring 205, whilering 206 seats under the interior shoulder in cylinder 207. Operatingshaft 203 is then connected to shell 21 1 by connection ring 213. Whenshaft 203 moves down, it will be seen that downward force I is exertedthrough shells 211, 210, ring 205, and spring 204 on ring 206.Similarly, upward movement of shaft 203 is transmitted through cylinder207, ring 206, spring 204, and ring 205. Thus, both upward and downwardmovement of shaft 203 is transmitted to shaft 177 throughshock-absorbing spring 204. This also makes the mechanism relativelyinsensitive to small dimensional changes such as produced bymisalignment and temperature changes.

FIGS. 25, 26 and 27 show plan views showing a three-pole dead tankcircuit breaker, each pole using the interrupters of FIGS. 1 and 2.Referring to FIGS. 25, 26 and 27, the breaker is made up of threeidentical single pole units 300, 301 and 302, each of which havebushings 303-304, 305-306 and 307-308, respectively. A control cabinet309 is secured with the poles and contains a suitable gas compressor andgas control equipment for supplying the individual pole units with gassuch as sulfur hexafluoride at the proper pressure, temperature andrequired conditions for cleanliness. Two high pressure gas storage tanks310 and 311 are located at the bottom of the breaker and receive theindividual poles and cabinet 309 as shown. Suitable heaters (not shown)and suitable thermal insulation may be provided for tanks 310 and 311,controlled from controls in cabinet 309 to maintain the gas in tanks 310and 311 at a high enough temperature to prevent excessive condensation.

FIGS. 28 and 29 show sectional views of pole 300 with the tank cut away.As shown in those figures, two interrupters eah identical to theinterrupters of FIGS. 1 and 2 are contained within the flattened steeltank 312 of each pole to form four series connected breakers for eachpole whereby the breaker can be used at operating voltages of 242KVmaximum line-to-line voltage on three-phase power systems. Similararrangements may be used for lower and higher voltages, e.g., 121 to 362KV. The tanks are formed by joining together, as by welding, twosections whose axes of revolution are the horizontal center lines ofeach tank assembly in such a way'that approximately equal clearance toground is achieved between all live parts and the tank surface. In thisway, a minimum volume of gas is used for a particular operating voltage.

The interrupting assemblies are supported on columns 14 which arefastened and supported by the pole unit mechanism 313 in such a way thatthe high pressure gas may be used to fill the support columns 14 up tothe blast valve 154 of FIGS. 1 and 2.

The terminal bushings 303 and 304 extend down from the top of tank 312and support the stationary contacts of the outer interrupters (contact53 of FIG. 2). Bushings 303 and 304 may be insulated internally bycompressed gas, or may be of the solid core design.

An insulating column 314 (FIGS. 28 and 29) is supported at the top ofthe tank 312 and extends downwardly to support the stationary contactsof the two interior interrupters. Insulation operating rods,corresponding to operating rod 203 of FIG. 1, extend down through thesupport columns 14 of each of the interrupters and are connected tooperating rod 315 through a crank mechanism 316 to operating rod 317.Rod 317 is connected to a bell crank assembly 318 which extends intocontrol cabinet 309 (FIG. 29). Rod 317 is sealed by a flexible bellows319, so that no sliding seals are used between the operating mechanismand the moving partswithin each of the pole units. All the moving partsof each of the pole units are connected by rigid metal rods which passthrough piping 320 which may be metallic and welded to the individualtanks. Thus, all moving contacts are, in effect, connected to oneoperating mechanism in the control cabinet, using only the singleflexible bellows 319. This minimizes the hazard of leakage of gas fromthe tanks or into the tanks.

Referring to FIG. 28, the bushings 303 and 304 enter tank 312 throughconductive cylinders 330 and 331, respectively, which have end rings 332and 333, respectively, fastened to their bottoms. Cylinders 330 and 331are formed in such'a manner that a relatively uniform electrostaticfield distribution is obtained along the lower surface of the housing303 and 304 and between the outside of shields 15 and 16 and the wall oftank 312. This is obtained by the symmetry shown and properproportioning of the lower bushing termination and the inside surface ofcylinders 330 and 331.

FIG. 30 shows a detailed view, partly in cross-section of a gas filledbushing which can be used for bushing 303 and cylinder 330 which isbolted to insulation column 340 as by bolts such as bolt 341. The mainconductor 342 is fastened to a lower thrust plate 343'and an upperthrust plate and spring assembly 344 as by threading, to connect upperand lower insulation portions 345 and 346 together by compressiveforces. The lower end of the bushing is surrounded by shield 15 of FIGS.1, 2 and 28. The lower end of cylinder 330 is terminated by the ring 332which is in a plane normal to the axis of the bushing to provide arelativelyv uniform field between bushing 340 and tank 312, even thoughthe bushing 303 passes through the tank wall at an oblique angle which.otherwise would result in anonuniform three-dimensional field. Thus, inFIG. 28, it is seen that it would be highly advantageous to. arrange thebushings, tanks and bushing cylinders in this way to maintain adequateelectrical clearance between the top ends of the bushings in atmosphericair, and, atthe same time, achieve the required electrical clearanceinside the tanks between live parts across the breaks; between liveparts and ground parts; and at the same time achievinga minimum diameterand volume for tank 300.

FIG. 30 schematically shows a grading ring 350 disposed around the lowerend of insulator portion 345 which is electrically connected to cylinder330 which may be used to modify the electrostatic flux distributionaround the top of the connecting flange 351 of insulator portion 345 andthe flange 351 when mounted on the tank 312.

FIG. 30 also shows the equipotential lines of electrostatic flux in 10increments when conductor 342 is energized and tank 312 is grounded. Itwill be seen that a nearly uniform tangential stress distribution isachieved along the surfaces of insulator portion 346, and a uniformradial stress is obtained between shield 15 and tank 312 and ring 332.Note that the relatively simple ring 332 is very effective in reducingthe high local stresses at the junction between tank 312 and cylinder330 which are inherent in the usual commercial joining operation.

Referring to FIGS. 28 and 29, suitable current transformers 360 and 361are disposed around the exterior portions of bushings 303 and 304.Toroidal shaped grading rings 362 and 3 63, respectively, are disposedabove current transformers 360 and 361, respectively, and serve the samefunctions as ring 350 of FIG. 30. The leads of the various currenttransformers 360 and 361 are connected within weatherproof junctionboxes 364 and pass through conduits 365, 366 and 367 to beinterconnected to one another and to the control housing 309. Conduits364, 365 and 366 are rigid pipes which further serve to brace the topends of the pole units 300, 301 and 302.

The connection of high and low pressure gas to the various parts of thesystem is best shown in FIG. 31. Thus, two conduits 370 and 371 extendfrom control cabinet 309 to tanks 310 and 311 to a high pressure. Thetanks 310 and 31 1 are then connected by conduits 372 and 373 to thebottom, and interior of support insulators 14, FIGS. 28 and 29. Thus,high pressure tanks 310 and 311, support insulators 14 and interruptertanks 13 are charged with high pressure sulfur hexafluoride gas at about250 p.s.i.g. The interior of the large main tank 312 is maintained at arelatively low gas pressure such as 45 p.s.i.g., through conduit 375which connects the tank 312 closest to cabinet 309 to the low pressurecontrols of cabinet 309. The remaining tanks of poles 301 and 302 aremaintained at this same relatively low pressure by conduits 376 whichcommunicate between the various tanks.

FIGS. 32 and 33 show details of portions of the operating mechanismshown in FIGS. 28 and 29. In FIGS. 32 and 33, there is provided amounting plate 380 which carries a plurality of bearings 381 forrotating shaft and lever assembly 315 (see FlGS. 28 and 29 and lever316). The bearings 381 are fastened to plate 380 and guide the shaftassembly 315 and permit rotational movement around the center line ofshaft assembly 315.

Link or crank 316 is pivotally connected to link 317, while its otherend is connected to shaft 203 (FIGS. 1 and 2). Link 317 extends throughthe bearing and gland assembly 319 which is suitably bolted to plate 380and sealed thereto by seal 382. A gas seal 383 is maintained under fixedaxial load by spring 384. A bearing 385 which may be of a suitable lowfriction self-lubricating material guides the lower end of link 317, andmay be of Teflon. A similar material may be used for all other bearingsand guides inside the breaker, e.g., components 170, 184, 192, 107, 108and 125. This eliminates the need for bearing lubrication and minimizesthe abrasive effect of any particles produced by a power are such asmetallic fluorides which may be produced when sulfur hexafluoride isexposed to a power arc.

FIGS. 29 and 31 show an accelerating spring assembly 390 located in eachtank assembly which biases the linkage assembly including link 317toward the breaker open position. Accelerating spring assembly 390includes suitable compressive springs with suitable resilientover-travel stops to minimize decelerating forces at the end of theclosing operation. This balances the accelerating forces betweenindividual pole units and locates the stored energy in the springs closeto the moving contacts without requiring transmission of high closingforces through the insulated operating rod 203.

When closing, the forces are transmitted from the operating mechanism incabinet 309 through the metallic operating rods such as rod 317 into theaccelerating opening springs 390. The insulated rod 203 need onlytransmit the relatively low compressive force required to accelerate theinterrupter parts on closing and to overcome frictional and gas-pressureforces.

During opening, the accelerating forces are transmitted from mechanism313 to the shaft assembly 315 and the insulating rod 203 transmits onlythe tension force required to accelerate the interrupter parts andovercome frictional and gas-pressure forces.

An additional compression accelerating spring 395 (FIG. 29) is locatedinside control cabinet 309 which also pushes the contacts toward theiropen position. Spring 309 is adjustable and permits minor adjustments ofopening speeds of all moving contacts without requiring access topressurized parts of the breaker. A dashpot 396, shown in FIG. 29, issuitably located to reduce acceleration forces produced at the end ofthe opening stroke.

Although this invention has been described with respect to its preferredembodiments, it should be understood that many variations andmodifications will now be obvious to those skilled in the art, and it ispreferred, therefore, that the scope of the inventionbe limited not bythe specific disclosure herein, but only by the appended claims.

The embodiments of the invention in which an exclusive privilege orproperty is claimed are defined as follows:

1. A movable arcing chamber for a high voltage gas blast circuitbreaker; said circuit breaker comprising: a stationary contact having acentral opening therethrough, a main annular body and an axiallyextending neck section having an outside diameter smaller than theoutside diameter of said main annular body, and a radially directedshoulder joining said outside diameter of said main annular body andsaid outside diameter of said extending neck section; an elongatedmovable contact including a plurality of contact fingers arrangedcoaxially with the axis of said central opening in said stationarycontact and moving axially into and out of engagement with said outsidediameter of said stationary contact neck section; first support meansfor supporting said stationary contact; second support means forslidably supporting said movable contact; and operating means connectedto said movable contact for axially moving said movable contact into andout of engagement with said stationary contact; said movable arcingchamber comprising an insulation cylinder slidably mounted on saidsecond support means and concentrically surrounding said movablecontact; means for releasably coupling said movable contact and saidmovable arcing chamber when said movable contact moves toward engagementwith said stationary contact; one end of said movable arcing chamberengaging and sealing against said shoulder of said stationary contactwhen said movable contact engages said stationary contact, thereby toform a sealed chamber interiorly of said movable arcing chamber; biasingmeans normally biasing said movable arcing chamber away from saidstationary contact; and a blast valve and a source of high pressure gas;said source of high pressure gas connected to said sealed chamberthrough said blast valve; said blast valve movable from a closed to anopen position; said blast valve connected to said operating means foroperating said blast valve between its said open and closed positions;said blast valve mechanically connected to said movable contact.

2. The device as set forth in claim 1, wherein said movable contactincludes an elongated hollow conductive tube for mounting said pluralityof contact fingers; the end of said tube adjacent said contact fingerscommunicating with saidcentral opening in said stationary contact andbeing external of said sealed chamber.

3. The device as set forth in claim 1, wherein said movable arcingchamber includes an inwardly projecting section on the end surfacethereof exposed to the high pressure in the interior of said arcingchamber, thereby to hold said arcing chamber sealed to said stationarycontact after said movable contact separates from said stationarycontact, and subsequently moving away from said stationary contact dueto said housing biasing means only after the pressure in said chamberdecreases below a predetermined value.

1. A movable arcing chamber for a high voltage gas blast circuit breaker; said circuit breaker comprising: a stationary contact having a central opening therethrough, a main annular body and an axially extending neck section having an outside diameter smAller than the outside diameter of said main annular body, and a radially directed shoulder joining said outside diameter of said main annular body and said outside diameter of said extending neck section; an elongated movable contact including a plurality of contact fingers arranged coaxially with the axis of said central opening in said stationary contact and moving axially into and out of engagement with said outside diameter of said stationary contact neck section; first support means for supporting said stationary contact; second support means for slidably supporting said movable contact; and operating means connected to said movable contact for axially moving said movable contact into and out of engagement with said stationary contact; said movable arcing chamber comprising an insulation cylinder slidably mounted on said second support means and concentrically surrounding said movable contact; means for releasably coupling said movable contact and said movable arcing chamber when said movable contact moves toward engagement with said stationary contact; one end of said movable arcing chamber engaging and sealing against said shoulder of said stationary contact when said movable contact engages said stationary contact, thereby to form a sealed chamber interiorly of said movable arcing chamber; biasing means normally biasing said movable arcing chamber away from said stationary contact; and a blast valve and a source of high pressure gas; said source of high pressure gas connected to said sealed chamber through said blast valve; said blast valve movable from a closed to an open position; said blast valve connected to said operating means for operating said blast valve between its said open and closed positions; said blast valve mechanically connected to said movable contact.
 2. The device as set forth in claim 1, wherein said movable contact includes an elongated hollow conductive tube for mounting said plurality of contact fingers; the end of said tube adjacent said contact fingers communicating with said central opening in said stationary contact and being external of said sealed chamber.
 3. The device as set forth in claim 1, wherein said movable arcing chamber includes an inwardly projecting section on the end surface thereof exposed to the high pressure in the interior of said arcing chamber, thereby to hold said arcing chamber sealed to said stationary contact after said movable contact separates from said stationary contact, and subsequently moving away from said stationary contact due to said housing biasing means only after the pressure in said chamber decreases below a predetermined value. 